Search engines and search services are becoming staples of user interaction with the Internet, and as the wealth of information available online increases, so too does people's reliance on effective and efficient search services for a multitude of projects and situations. Recent research indicates that the majority of time spent by computer users interacting with search services is spent in long search sessions that involve many search queries and selections of search results. Moreover, the data suggests that users spend a significant portion of long search sessions trying to re-find content that they have already viewed.